OW Cert w/o learning Dive Tables?!?!?

[Blackwood]

You show them tables, you work through examples, you point things out such as decreasing time with depth and so on. You put real figures to it so they appreciate it. You show them off gassing/surface interval charts so they get a feel for it. You work examples to put real figures into it to make it real. Pressure gradients have to be mentioned - its the whole point of it. You mention compartments and how the body is "made" up of several pseudo compartments. Knowledge like that is essential so they *understand* the topic.

I disagree. For most people, I think that simplicity is safer. If they are thinking about the why they may gloss right over the what.

I'd like a simple presentation of tables and trends in Basic Open Water. (e.g. "The deeper you go, the shorter your stay. The longer your stay, the more you ongas, etc.").

Compartmental analysis should be limited to a discussion about ascent rates and stops (e.g. "There are fast tissues and there are slow tissues").

Anything more, and the parts of decompression theory useful to recreational divers (the results) are going to seem less clear.

Those who wish to learn it more in depth are welcome to, but I think it's beyond the scope of basic open water, just like a discussion about planetary gearsets is beyond the scope of learning to drive a car with an automatic transmission.

Teach them how to plan a dive: These are your limits for deco, these are your limits for gas, etc.. Then teach them how to dive.

Being able to follow an arrow on a computer is one thing but its using not understanding which causes big issues with the computer does something it shouldnt do, is wrong, breaks or they borrow someone elses.

I guess, but since a diver on anything but a square profile is going to see markedly different results, I don't see how someone who has only been introduced to tables is capable of making an informed decision about the reliability of a computer.

A table you can see the spread of all times and all depths at once.

I agree. They would completely suffice if people held to square dives.

FWIW i dont think putting the padi table on here like that is a great idea. Copyright concerns etc.

Good point. Though it was hosted from some other site, linking to it here may be a no no. It's gone.

 

[String]

I'd like a simple presentation of tables and trends in Basic Open Water. (e.g. "The deeper you go, the shorter your stay. The longer your stay, the more you ongas, etc.").

It doesnt work that easily without figures. Firstly you just state something without going into reasoning its a sure-fire way to get ignored. Secondly they have no reference frame, they dont know how long is too long, how deep is too deep. They dont know if 5 minutes or 50 mins at 40m is fine or if "a little bit too long" is 1 minute ot 15. Tables provide a frame of reference in teaching to look at and by doing examples can help give them some sort of reference. This is invaluable later on for when their computer craps out or starts displaying incorrect information - they can sanity check it.

Teach them how to plan a dive: These are your limits for deco, these are your limits for gas, etc.. Then teach them how to dive.

and tables are the best way of doing that. Not all computers have planning modes, not all that do have it can plan multiple dives with specific or varying surface intervals. Tables make it much easier to plan, you look up a depth and read across a time. It never varies. It doesnt need batteries and it works all the time regardless of brand.

I guess, but since a diver on anything but a square profile is going to see markedly different results, I doubt that someone who has only been introduced to tables is capable of making an informed decision about the reliability of a computer.

They can be informed if through worked examples they have a basic frame of reference. If the computer is telling them they have 2hrs stop time remaining at 30m just from the problems theyve done on tables alarm bells should start ringing. WITHOUT giving them this reference they would have no idea whats sensible and what isnt and people end up following blindly.

I agree. They would completely suffice if people held to square dives.

You can plan non square dives with tables. In either case, square profile is a worst case scenario. Its the most conservative. It WILL get you out of jail when your computer dies.

 

[Blackwood]

It doesnt work that easily without figures. Firstly you just state something without going into reasoning its a sure-fire way to get ignored. Secondly they have no reference frame, they dont know how long is too long, how deep is too deep. They dont know if 5 minutes or 50 mins at 40m is fine or if "a little bit too long" is 1 minute ot 15. Tables provide a frame of reference in teaching to look at and by doing examples can help give them some sort of reference. This is invaluable later on for when their computer craps out or starts displaying incorrect information - they can sanity check it.


and tables are the best way of doing that. Not all computers have planning modes, not all that do have it can plan multiple dives with specific or varying surface intervals. Tables make it much easier to plan, you look up a depth and read across a time. It never varies. It doesnt need batteries and it works all the time regardless of brand.

I know. Again, I'm not advocating the removal of tables from class. I'm simply questioning the wisdom of spending time (which is limited) teaching people something that they may never use.

You can plan non square dives with tables. In either case, square profile is a worst case scenario. Its the most conservative. It WILL get you out of jail when your computer dies.

I know you can. I do it all the time. And I also track my average depth throughout my dives.

Do you teach OW students how to plan multilevel dives with tables? If so, that's great.

 

[noobascooba]

We are speaking about idiots, the population whose IQ is between 50 and 80.

Give them a timer and a depth gauge, and they can't tell you how to figure out what is 30 ft per minute ascent rate. These are the same idiots who add air to their BC to ascent rather than subtract air.

The computer will give them a visual reference of their ascent rate.

Idiots who can see GREEN - GO, RED - NO. YELLOW - you are almost in trouble- as when or how close they are to the NDL.

Idiots who surfaced and has no idea what their bottom time is.

Idiots who don't have a dive watch nor a dive computer.

Idiots who run out of air because they didn't check their SPG.

For these idiots, air integrated computers will beep when their tank gets low.

The technology is getting pretty advanced, and I wouldn't spend the money on it.... But some computers are as idiot proof as NOT HAVING ANY buttons at all.

Idiots... and people like me who are a little number blind and struggle to relate numbers on gauges to real life concepts. It takes a lot of concentration for me....

BUT I still use tables as well as my computer. When you don't have a clear concept of wether your computer is giving you a sensible ndl, it's good to use the table as a reality check. Admittadly I have to fudge the tables a bit, like not using the maximum depth if I haven't dived a square profile, but I'd still rather use them than not. Each to their own. Just remember, we're not all stupid. Some of us have phds but still struggle with numbers on dials

 

[String]

I know. Again, I'm not advocating the removal of tables from class. I'm simply questioning the wisdom of spending time (which is limited) teaching people something that they may never use.

I dont think its possible to separate tables from deco theory, they compliment each other. Removing tables would remove a teaching aid and hinder understanding of the former.

Do you teach OW students how to plan multilevel dives with tables? If so, that's great.

No. We keep it simple and assume square profile. In fact the BSAC 88 tables are only certified for square.
Its far simpler for them to only worry about square profile at that stage. And its a solution that will get them out of any situation as its the most conservative approach.

 

[Blackwood]

No. We keep it simple and assume square profile. In fact the BSAC 88 tables are only certified for square.
Its far simpler for them to only worry about square profile at that stage. And its a solution that will get them out of any situation as its the most conservative approach.

I do an air dive to 82' for 5 minutes and 20' for 45 minutes. On exit, a wave tumbles me and I smash my computer on a rock. I pull out my trusty backup (tables) and since I don't know how to account for multi-level profiles I am WELL into deco (90 for 50).

So do I grab my full tank and hit the water to make up 30 minutes of missed stops (assuming I have a table detailed enough to tell me)?

If I simply stop diving the tables don't solve anything for me. They aren't my conservative solution. Not diving is.

Sure, there may be times when you dive a multi-level profile that doesn't put you past square limits. In those cases, tables are a conservative solution to faulty electronics. For me anyway, these dives are extremely uncommon.

 

[String]

On exit so i assume you're on the surface?

Answer to that is assume square profile, look at tissue code. Look at surface interval chart and go from there. In that case on PADI i believe you'd be a Z but i havent got tables here to check so involves waiting a few hours.

With the "computer only" solution you're screwed totally as its broken. You dont have the knowledge or kit to do a second dive. With tables you get a longer lunch break but get a second dive.

 

[Sylvain]

I have a computer and still use my dive table before every dive and check my interval on both the computer and dive table. A computer is just that a computer better be safe than sorry and if for any reason my computer goes KAPUT then I know what my limits are and I can keep on diving as long as I stay within the limit of the pre-dive plan.

Just think, we don't need to build stairs in building because the technology is there to have only elavator but WHAT DO YOU DO IN CASE OF FIRE????? You go back to the OLD way and use the stairs and if the elavator breaks..... well you get the drift.....

 

[Temple of Doom]

Answer to that is assume square profile, look at tissue code. Look at surface interval chart and go from there. In that case on PADI i believe you'd be a Z but i havent got tables here to check so involves waiting a few hours.

Using the padi tables and a square profile of 82' for 55 minutes puts you 27 min past your no-deco limits (no groupings apply when you are past your no-deco, you are 'off the padi charts'). When you're off the charts of a PADI table, the following information written on the back of the table itself applies:

If a no decompression limit is exceeded by no more than 5 minutes, an 8 minute decompression stop at 15ft is mandatory. Upon surfacing, the diver must remain out of the water for at least 6 hours prior to making another dive. If a no decompression limit is exceeded by more than 5 minutes, a 15ft decompression stop of no less than 15 minutes is urged (air supply permitting). Upon surfacing, the diver must remain out of the water for at least 24 hours prior to making another dive.

I'm sure that if you exceed the NDL by 27 minutes with no deco stop, the PADI table would say something like: "you gonna die", not "wait a few hours then dive again"...

Craig

 

[Blackwood]

I'm sure that if you exceed the NDL by 27 minutes with no deco stop, the PADI table would say something like: "you gonna die", not "wait a few hours then dive again"...

Right. Most tables don't tell you what do to. The back side of my IANTD table says 3@20 and 26@15. I'm not sure what the BOW methodology is for roughly doubling NDL and not finding out until you've already surfaced (assume with an empty tank)

In any case, if you simply don't dive, your tables didn't do anything for you (them telling you not to dive is no different than you not diving because you are inadequately equipped).